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Journal Articles

New precise measurement of muonium hyperfine structure interval at J-PARC

Ueno, Yasuhiro*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 238(1), p.14_1 - 14_6, 2017/11

 Times Cited Count:2 Percentile:12.39

Journal Articles

New muonium HFS measurements at J-PARC/MUSE

Strasser, P.*; Aoki, Masaharu*; Fukao, Yoshinori*; Higashi, Yoshitaka*; Higuchi, Takashi*; Iinuma, Hiromi*; Ikedo, Yutaka*; Ishida, Keiichi*; Ito, Takashi; Iwasaki, Masahiko*; et al.

Hyperfine Interactions, 237(1), p.124_1 - 124_9, 2016/12

 Times Cited Count:5 Percentile:6.11

Journal Articles

Model magnet development of D1 beam separation dipole for the HL-LHC upgrade

Nakamoto, Tatsushi*; Sugano, Michinaka*; Xu, Q.*; Kawamata, Hiroshi*; Enomoto, Shun*; Higashi, Norio*; Idesaki, Akira; Iio, Masami*; Ikemoto, Yukio*; Iwasaki, Ruri*; et al.

IEEE Transactions on Applied Superconductivity, 25(3), p.4000505_1 - 4000505_5, 2015/06

Recently, development of superconducting magnet system with high radiation resistance has been demanded for application in accelerator facilities such as CERN LHC. In order to realize superconducting magnet system with high radiation resistance, it is necessary to develop electrical insulator with high radiation resistance because the electrical insulator is made of organic materials whose radiation resistance is inferior to that of inorganic materials. We developed a glass fiber reinforced plastic with bismaleimide-triazine resin. The developed material showed excellent radiation resistance; the material evolved gases of 5$$times$$10 $$^{-5}$$mol/g and maintained flexural strength of 640MPa (90% of initial value).

Journal Articles

Measurement of the displacement cross-section of copper irradiated with 125 MeV protons at 12 K

Iwamoto, Yosuke; Yoshiie, Toshimasa*; Yoshida, Makoto*; Nakamoto, Tatsushi*; Sakamoto, Masaaki*; Kuriyama, Yasutoshi*; Uesugi, Tomonori*; Ishi, Yoshihiro*; Xu, Q.*; Yashima, Hiroshi*; et al.

Journal of Nuclear Materials, 458, p.369 - 375, 2015/03

 Times Cited Count:5 Percentile:52.19(Materials Science, Multidisciplinary)

To validate Monte Carlo codes for the prediction of radiation damage in metals irradiated by $$>$$100 MeV protons, defect-induced electrical resistivity changes of copper related to the displacement cross-section were measured with 125 MeV proton irradiation at 12 K. The cryogenic irradiation system was developed with a Gifford-McMahon cryocooler to cool the sample via an oxygen-free high-conductivity copper plate by conduction cooling. The sample was a copper wire with a 250$$mu$$m diameter and 99.999% purity sandwiched between two aluminum nitride ceramic sheets. The resistivity increase did not change during annealing after irradiation below 15 K. The experimental displacement cross-section for 125 MeV irradiation shows similar results to the experimental data for 1.1 and 1.94 GeV. Comparison with the calculated results indicated that the defect production efficiency in Monte Carlo codes gives a good quantitative description of the displacement cross-section in the energy region $$>$$ 100 MeV.

Journal Articles

Stress/strain effects on industrial superconducting composites

Ito, Takayoshi; Harjo, S.; Osamura, Kozo*; Hemmi, Tsutomu; Awaji, Satoshi*; Machiya, Shutaro*; Oguro, Hidetoshi*; Nishijima, Gen*; Takahashi, Koki*; Matsui, Kunihiro; et al.

Materials Science Forum, 681, p.209 - 214, 2011/05

 Times Cited Count:1 Percentile:38.13

Journal Articles

Radiation resistance of organic materials in superconducting magnets at 77 K; Mechanical properties

Nakamoto, Tatsushi*; Ohata, Hirokatsu*; Ogitsu, Toru*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Yamamoto, Akira*; Idesaki, Akira; Gokan, Mayo*; Morishita, Norio; Ito, Hisayoshi

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 31, 2007/02

Radiation resistance of organic materials used in superconducting magnets for a 50 GeV - 750 kW proton beam line for the J-PARC neutrino experiment was studied with respect to mechanical properties. Specimens cooled at a liquid nitrogen temperature of 77 K were irradiated by $$gamma$$ rays. The flexural strength of glass-fiber reinforced plastics (GFRPs), the tear strength of polyimide films and the tensile strength of adhesive films were evaluated. It was verified that the organic materials used in the superconducting magnets have the sufficient radiation resistance, and the degradation of thier mechanical properties after the 10 years operation was estimated to be negligible.

Journal Articles

Radiation resistance of organic materials in superconducting magnets at 77K; Gas evolution

Idesaki, Akira; Gokan, Mayo*; Morishita, Norio; Ito, Hisayoshi; Nakamoto, Tatsushi*; Ogitsu, Toru*; Ohata, Hirokatsu*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Yamamoto, Akira*

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 32, 2007/02

Radiation resistance of polymeric materials used in the superconducting magnets installed for the J-PARC neutrino beam line was studied with respect to gas evolution. The polymeric materials were irradiated by $$gamma$$ rays at 77K. It was found that hydrogen gas evolved mainly from the polymeric materials, and the amount of hydrogen from whole superconducting magnet system per 1 year was estimated to be 0.37mol. This amount of hydrogen is low enough to be removed by a hydrogen absorbing apparatus. Therefore, the influence of hydrogen evolved from the magnet system on the operation of the helium purifying system can be negligible.

Journal Articles

Operation test result of a radio-proof cryogenic valve under cobalt 60 irradiation

Makida, Yasuhiro*; Ohata, Hirokatsu*; Okamura, Takahiro*; Ogitsu, Toru*; Nakamoto, Tatsushi*; Kimura, Nobuhiro*; Idesaki, Akira; Gokan, Mayo*; Morishita, Norio

JAEA-Review 2006-042, JAEA Takasaki Annual Report 2005, P. 34, 2007/02

A string of superconducting magnets is to be set at an arc section of the J-PARC neutrino beam line. To keep the magnets at superconducting condition, a helium cryogenic facility is to be constructed. Parts of cryogenic devices are located beside the magnets, so thier resistance to radiation with predicted dose of 1 MGy in maximum must be assured. A cryogenic control valve is one of the active devices used in the radio-active area, and its radio-proof characteristics is improved by (1) exchaging intolerant materials by proof ones, (2) moving the feed back control circuit unit including electronics from the valve body to a low radio-active area. Two prototype valves, a tuning valve and a Gauzky relief valve, have been prepared and have been tested by using the Cobalt 60 irradiation facility in JAEA. Actual operations of the both prototypes have been checked at the irradiation test bench, and they were successfully operated after irradiation of 1 MGy.

Oral presentation

$$gamma$$-ray irradiation effects on polymeric materials in superconducting magnets for the J-PARC neutrino experiment, 2; Gas evolution

Idesaki, Akira; Gokan, Mayo*; Morishita, Norio; Ito, Hisayoshi; Nakamoto, Tatsushi*; Ogitsu, Toru*; Ohata, Hirokatsu*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Yamamoto, Akira*

no journal, , 

Irradiation effect on polymeric materials used in the superconducting magnets for the J-PARC neutrino beam line was studied with respect to gas evolution. The polymeric materials were irradiated by $$gamma$$-ray at 77K. It was found that hydrogen gas evolves mainly from the polymeric materials, and that the amount of hydrogen from whole superconducting magnet system per 1 year is 0.37mol. Furthermore, it was found that the amount of gas evolution increases with increasing in the storage time at room temperature after the irradiation at 77K.

Oral presentation

$$gamma$$-ray irradiation effects on polymeric materials in superconducting magnets for the J-PARC neutrino experiment, 1; Mechanical properties

Idesaki, Akira; Nakamoto, Tatsushi*; Ogitsu, Toru*; Ohata, Hirokatsu*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Yamamoto, Akira*; Gokan, Mayo*; Morishita, Norio; Ito, Hisayoshi

no journal, , 

Radiation resistance of polymeric materials used in superconducting magnets for a 50 GeV-750 kW proton beam line for the J-PARC neutrino experiment was studied with respect to mechanical properties. Specimens were irradiated by $$gamma$$ rays with the maximum dose beyond 10 MGy. It was verified that the polymeric materials have the sufficient radiation resistance, and the degradation of their mechanical properties after the 10 years operation was estimated to be negligible.

Oral presentation

Superconducting magnet system for the J-PARC neutrino experiment, 12; Development of a radio-proof control valve and a relief valve

Makida, Yasuhiro*; Iida, Masahisa*; Ohata, Hirokatsu*; Okamura, Takahiro*; Ogitsu, Toru*; Kimura, Nobuhiro*; Tanaka, Kenichi*; Nakamoto, Tatsushi*; Yamamoto, Akira*; Idesaki, Akira; et al.

no journal, , 

A Superconducting magnet system will be adopted for the J-PARC neutrino beam line. Since the magnet system will be exposed to high radiation field, the radiation resistance of a cryostat is very important. We have developed radio-proof control valve and relief valve by selection of some parts and separation of the positioner. In this work, the developed valves were worked under the $$gamma$$ ray irradiation, and it was found that the valves show the radiation resistance above 1MGy.

Oral presentation

Superconducting magnet system for the J-PARC neutrino experiment, 13; $$gamma$$-ray irradiation effects on organic materials at 77 K

Nakamoto, Tatsushi*; Ohata, Hirokatsu*; Ogitsu, Toru*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Yamamoto, Akira*; Idesaki, Akira; Ito, Hisayoshi; Morishita, Norio

no journal, , 

A Superconducting magnet system will be adopted for the J-PARC neutrino beam line. GFRPs whose matrices are phenol resin and epoxy resin, and polyimides are used as structural materials and electrical insulation. Radiation resistance of these polymeric materials is very important, because they are exposed to high radiation field. In this work, specimens were irradiated by $$gamma$$ rays with the maximum dose beyond 10MGy at liquid nitrogen temperature (77K), and the properties of gas evolution and mechanical strength were investigated. It was verified experimentally that the polymeric materials have sufficient radiation resistance for the using in the J-PARC neutrino beam line.

Oral presentation

$$gamma$$-ray irradiation effects on polymeric materials in superconducting magnets; Gas evolution

Idesaki, Akira; Gokan, Mayo*; Morishita, Norio; Ito, Hisayoshi; Nakamoto, Tatsushi*; Ogitsu, Toru*; Ohata, Hirokatsu*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Yamamoto, Akira*

no journal, , 

Irradiation effect on polymeric materials used in the superconducting magnets for the J-PARC neutrino beam line was studied with respect to gas evolution. The polymeric materials were irradiated by $$gamma$$-ray at 77K. It was found that hydrogen gas evolves mainly from the polymeric materials, and that the amount of hydrogen from whole superconducting magnet system per 1 year is 0.37 mol.

Oral presentation

$$gamma$$-ray irradiation effects on polymeric materials in superconducting magnets; Mechanical properties

Nakamoto, Tatsushi*; Ohata, Hirokatsu*; Ogitsu, Toru*; Kimura, Nobuhiro*; Makida, Yasuhiro*; Yamamoto, Akira*; Idesaki, Akira; Gokan, Mayo*; Morishita, Norio; Ito, Hisayoshi

no journal, , 

A Superconducting magnet system will be adopted for the J-PARC neutrino beam line. GFRPs whose matrices are phenol resin and epoxy resin, and polyimides are used as structural materials and electrical insulation. Radiation resistance of these polymeric materials is very important, because they are exposed to high radiation field. In this work, specimens were irradiated by $$gamma$$ rays with the maximum dose beyond 10 MGy at liquid nitrogen temperature (77K), and the mechanical properties were investigated. It was verified experimentally that the polymeric materials have sufficient radiation resistance for the using in the J-PARC neutrino beam line.

Oral presentation

Development of a radio-proof control valve and a relief valve; Driving test under the irradiation

Makida, Yasuhiro*; Ohata, Hirokatsu*; Okamura, Takahiro*; Ogitsu, Toru*; Nakamoto, Tatsushi*; Kimura, Nobuhiro*; Idesaki, Akira; Gokan, Mayo*; Morishita, Norio

no journal, , 

A Superconducting magnet system will be adopted for the J-PARC neutrino beam line. Since the magnet system will be exposed to high radiation field, the radiation resistance of a cryostat is very important. We have developed radio-proof control valve and relief valve by selection of some parts and separation of the positioner. In this work, the developed valves were worked under the $$gamma$$ ray irradiation, and it was found that the valves show the radiation resistance above 1 MGy.

Oral presentation

Study of measurement of displacement cross section for copper irradiated with 125 MeV proton

Iwamoto, Yosuke; Yoshida, Makoto*; Nakamoto, Tatsushi*; Ogitsu, Toru*; Yoshiie, Toshimasa*; Sakamoto, Masaaki*; Kuriyama, Yasutoshi*; Uesugi, Tomonori*; Ishi, Yoshihiro*; Mori, Yoshiharu*

no journal, , 

We measured the electrical resistivity under irradiation of 125 MeV proton in copper sample (0.2 um thickness) at cryogenic temperature at the FFAG accelerator facility in Kyoto university. Resistivity was measured by the four-terminal method. As a result, we measured the resistivity of copper at 7.3 K within 20 micro-ohm and temperature of sample. We measured the electrical resistivity under irradiation of 125 MeV proton in copper sample (0.2 um thickness) at cryogenic temperature at the FFAG accelerator facility in Kyoto university. Resistivity was measured by the four-terminal method. As a result, we measured the resistivity of copper at 7.3 K within 20 micro-ohm and temperature of sample.

Oral presentation

Development of the device for electrical resistivity measurements for proton irradiation under cryogenic condition

Iwamoto, Yosuke; Yoshiie, Toshimasa*; Yoshida, Makoto*; Nakamoto, Tatsushi*; Sakamoto, Masaaki*; Kuriyama, Yasutoshi*; Uesugi, Tomonori*; Ishi, Yoshihiro*; Xu, Q.*; Yashima, Hiroshi*; et al.

no journal, , 

To validate the radiation damage calculation in the PHITS code for proton irradiation over 100 MeV, we have developed the device for electrical resistance measurement under cryogenic condition. A copper wire with 99.999% purity in a diameter of 250-$$mu$$m was set with a serpentine-shaped line on the AlN sheet which has high thermal conductivity and electric insulation. The sample was annealed for 1 h at 1,000$$^{circ}$$C before irradiation. After annealing, the sample was cooled with an oxygen-free high-conductivity copper plate by conduction cooling. The electrical resistivity changes in the sample were measured using the four-probe technique. As a result, the residual resistivity ratio of the sample was about 1,800 between room temperature and 11 K. After 125 MeV proton irradiation with 1.45$$times$$10$$^{14}$$(proton/cm$$^{2}$$) at 11 K, the total resistance increase was 1.53$$mu$$ $$Omega$$, while the resistivity of copper before irradiation was 29.41$$mu$$ $$Omega$$.

Oral presentation

Measurement of the damage rate of copper irradiated with 125 MeV protons at 12 K and comparison with calculated result with the PHITS code

Iwamoto, Yosuke; Yoshiie, Toshimasa*; Yoshida, Makoto*; Nakamoto, Tatsushi*; Sakamoto, Masaaki*; Kuriyama, Yasutoshi*; Uesugi, Tomonori*; Ishi, Yoshihiro*; Xu, Q.*; Yashima, Hiroshi*; et al.

no journal, , 

To validate Monte Carlo code PHITS for the prediction of radiation damage in metals, the damage rate (defect-induced electrical resistivity changes / particle fluence) related to the displacement cross-section of copper were measured with 125 MeV proton irradiation under 12 K at the FFAG facility in the Kyoto University Research Reactor Institute. The sample was a copper wire with a 250-$$mu$$m diameter and 99.999% purity and was cooled by conduction cooling. After 125 MeV proton irradiation with 1.45$$times$$10$$^{18}$$ protons/m$$^{2}$$ at 12 K, the total resistivity increase was 4.94$$times$$10$$^{-13}$$$$Omega$$m (resistance increase: 1.53$$mu$$$$Omega$$), while the resistivity of copper before irradiation was 9.49 $$times$$10$$^{-12}$$$$Omega$$m (resistance: 29.41$$mu$$$$Omega$$). Comparison with other experimental results indicated that the damage rate by 125 MeV protons is almost same with those by 1.1 GeV protons and is higher than the damage rate by 14 MeV neutrons by a factor of 1.4. For the comparison with the PHITS results, the experimental data is smaller than the calculated result without the defect production efficiency by a factor of about 2.5 and that with the defect production efficiency by a factor of about 1.4, respectively. It indicates that the defect production efficiency in PHITS gives a good quantitative description of the displacement cross-section.

18 (Records 1-18 displayed on this page)
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